You can't go wrong with the Indy boot. The chukkas are dressier, so your need will determine which of the two you choose to buy. If money is not a concern, buy both
Feel free to visit also, our Alden Thread over at the Streetwear section of Styleforum, here: http://www.styleforum.net/t/85589/the-official-alden-thread/0_50
This link will take you to page 01 of that thread, so if you like, you can select the last page and go from there, or browse the thread. Enjoy.